In recent years attempts have been made to reduce the amount of pollutants/emissions released from combustion of fuels. Examples of pollutants include sulphur oxides (e.g. sulphur trioxide), nitrogen oxides, carbon monoxide, carbon dioxide and particulate matter. These pollutants are known to adversely affect levels of green-house gases or contribute to other problems, such as, smog. In the case of particulate matter, studies have also indicated adverse effects on human, animal and plant well being. Other by-products of fuel combustion include vanadate deposits. Vanadate deposits are believed to form corrosive low-melting slag that forms deposits. It would be desirable to combust fuels whilst keeping pollutants and deposits such as those mentioned above to a minimum.
International Publication WO 2005/097952 discloses providing a fuel composition containing a metal base with a solids content of greater than about 35 wt % of the dispersion. The composition disclosed employs one metal base per dispersion.
International Publication WO 04/026996 discloses a fuel additive composition capable of reducing vanadate deposits. The composition contains a metal inorganic oxygen containing compound, a liquid soluble in oil and a dispersant including fatty acid or ester derivatives thereof.
Some of the problems encountered in using dispersions in fuel-related applications relates to their material handling properties, and particularly their ability to be pumped as well as their ability to be remain homogenous, keeping the metals entrained in the dispersion in the mixture and preventing them from dropping out or becoming very viscous and difficult to handle. These handling and pumping issues can be generally related to a dispersions viscosity and particle size distribution, which are also interconnected. The higher the viscosity and the larger the particle size distribution of the dispersion, the worse the handling properties and the harder the dispersion and dispersion-containing fuel compositions are to store, use and pump, and so the less effective the dispersion. These problems not only make the dispersions and the fuels they go into more difficult to pump and handle but also less effective in providing the benefits and improvements to engine and burner operation.
There is a continued need for dispersions for use in fuel related applications, and more particularly there is a need for dispersions that have improved handling properties. The present invention provides dispersions that have improved handling characteristics as well as methods for providing and using such dispersions.